Apparatus for filling heat storage material

ABSTRACT

An apparatus for filling a heat storage material in a heat storage system for thermal energy delivery business is provided, wherein the heat storage system stores waste heat and is then moved a location where the heat is to be used, to dissipate the heat. According to the apparatus for filling a heat storage material, an accurate and uniform amount of a phase change material may be conveniently filled in the heat storage system while maintaining a liquid state of the heat storage material by melting the phase change material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2018-0056864, filed on May 18, 2018, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND 1. Field

One or more embodiments relate to an apparatus for filling a heatstorage material, and more particularly, to an apparatus for filling aheat storage material in a heat storage system for thermal energydelivery business, wherein the heat storage system stores waste heat andis then moved a location where the heat is to be used, to dissipate theheat.

2. Description of the Related Art

A foray has been made into a thermal energy delivery business of storingwaste heat generated in factories such as steel mills and supplying theheat to greenhouses or homes, and such heat has been used in some areas.

In the thermal energy delivery business, waste heat generated fromheating furnaces or incinerator chimneys of a factory such as steelmills is stored for use. As a medium that stores waste heat, a phasechange material (PCM) which is a latent heat storage material or achemical heat storage material is used. By making a fluid such as a heatmedium oil that is heated by using waste heat, to flow through a heatstorage container storing the PCM, the PCM is changed to a liquid state,thereby storing heat.

An apparatus for storing heat by using the PCM is called a heat storagesystem. The heat storage system stores heat by using a PCM filled in theheat storage system. Thus, a manufacture of a heat storage systemrequires an operation of filling a PCM in the heat storage system.

The PCM described above is available as solid particles. When filling aPCM in a solid state in a heat storage system, a filling efficiency islow due to air gaps between solid particles. Thus, it is effective tofill a PCM in a heat storage system by melting the PCM in a solid state.

When melting a PCM in a solid state and individually injecting the PCMin a heat storage system, the PCM injected relatively early is cooledand changed to a solid state. There is a difference in a volume of a PCMbetween a solid state and a liquid state. Thus, it is difficult to fillan accurate amount of PCM in a heat storage system by using theabove-described method.

Thus, there is a need for an apparatus for effectively filling a PCM ina heat storage system by effectively melting the PCM and maintaining aliquid state of the PCM.

SUMMARY

One or more embodiments include an apparatus for filling a heat storagematerial, wherein a uniform amount of a phase change material (PCM) maybe filled in a plurality of heat storage systems by using the apparatuswhile maintaining the phase change material (PCM) in a liquid state.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to one or more embodiments, an apparatus for filling a heatstorage material is provided, wherein the apparatus is formed in theform of a container for storing heat by using a thermal energy deliverymethod, wherein a heat storage material is filled in a heat storage unithaving an injection inlet formed in an upper portion of the heat storageunit, the apparatus including: a heating case including a fillingchamber having an opened upper portion, an inlet through which hot wateris supplied to the filling chamber, and an outlet formed in the fillingchamber, wherein the hot water that has flown into the filling chamberis discharged through the outlet; a holding frame including a holdingportion on which the heat storage unit is held, wherein the holdingframe enters an upper portion of the heating case to be seated in thefilling chamber of the heating case; a cover plate including a fillinghole communicating with the injection inlet of the heat storage unit soas to fill the heat storage material through the injection inlet of theheat storage unit, wherein the cover plate is coupled to the holdingframe.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a disassembled perspective view of an apparatus for filling aheat storage material, according to an embodiment of the presentdisclosure;

FIG. 2 is a perspective view of the apparatus for filling a heat storagematerial, illustrated in FIG. 1;

FIG. 3 is a perspective view of a holding frame of the apparatus forfilling a heat storage material, illustrated in FIG. 1;

FIG. 4 is a cross-sectional view of the apparatus for filling a heatstorage material illustrated in FIG. 2, taken along line IV-IV; and

FIG. 5 is a perspective view of a heat storage unit in which a heatstorage material is filled by using the apparatus for filling a heatstorage material illustrated in FIG. 1.

DETAILED DESCRIPTION

Hereinafter, an apparatus for filling a heat storage material accordingto an embodiment of the present disclosure will be described in detailwith reference to the attached drawings.

FIG. 1 is a disassembled perspective view of an apparatus for filling aheat storage material, according to an embodiment of the presentdisclosure. FIG. 2 is a perspective view of the apparatus for filling aheat storage material, illustrated in FIG. 1.

Referring to FIGS. 1 and 2, the apparatus for filling a heat storagematerial according to the present embodiment includes a heating case200, a holding frame 300, and a cover plate 500.

As a heat storage material, materials generally known as a phase changematerial (PCM) are used. When a heat storage material has absorbedexternal heat and is thus at a high temperature, the heat storagematerial is in a liquid state. When a temperature of the heat storagematerial is lowered as heat stored in the heat storage material isdissipated to the outside, then the heat storage material is in a solidstate.

According to the present embodiment, an apparatus for filling a heatstorage material, which is capable of simultaneously filling a heatstorage material into twelve heat storage units 100, will be describedas an example.

The apparatus for filling a heat storage material, according to thepresent embodiment, is an apparatus for filling a heat storage materialin the heat storage units 100 by melting a heat storage material in asolid state by using hot water filled in the heating case 200 afterhaving inserted the holding frame 300, on which the twelve heat storageunits 100 are held, into the heating case 200.

As illustrated in FIG. 1, the cover plate 500 is coupled to an upperportion of the holding frame 300, and the holding frame 300, to whichthe cover plate 500 is coupled, is inserted into the heating case 200.

The heating case 200 includes a filling chamber 210, an inlet 220, andan outlet 230. As illustrated in FIGS. 1 and 2, the filling chamber 210has an opened upper portion. The filling chamber 210 has a shape inwhich hot water may be filled. The filling chamber 210 may preferably beformed of a heat-retaining material so as to maintain a constanttemperature of the hot water filled in the filling chamber 210.

In the present embodiment, as illustrated in FIG. 2, the inlet 220 isarranged in a lower portion of the filling chamber 210, and the outlet230 is arranged in an upper portion of the filling chamber 210. Hotwater is supplied to the filling chamber 210 through the inlet 220, andthe hot water filled in the filling chamber 210 is discharged throughthe outlet 230.

The holding frame 300 includes a holding portion 310 and a gap member400. Referring to FIG. 1, the holding frame 300 is formed to enter theheating case 200 through an upper portion of the heating case 200 and tobe seated in the filling chamber 210. Referring to FIG. 3, the holdingframe 300 according to the present embodiment is formed of a metallicframe having a bar shape. Twelve heat storage units 100 are held insidethe holding frame 300. The holding portion 310 is arranged in a lowerportion of the holding frame 300 and supports lower surfaces of the heatstorage units 100.

The holding portion 310 includes twelve unit guides 311, which is thesame number as the heat storage units 100. As illustrated in FIG. 3, theunit guides 311 have a ring shape. A shape of the unit guides 311corresponds to a shape of the lower surfaces of the heat storage units100. A lower portion of the heat storage units 100 is inserted into theunit guides 311. The unit guides 311 are arranged at uniform distancesto arrange the twelve heat storage units 100 at uniform distances. Aninner diameter of the unit guides 311 is greater than a cross-section ofthe heat storage units 100 such that there is a distance between theheat storage units 100 inserted into the unit guides 311 and the unitguides 311.

As illustrated in FIG. 3, four gap members 400 are installed on an uppersurface of the holding frame 300. The cover plate 500, which will bedescribed later, is coupled to the holding frame 300 via the gap members400. Due to the gap members 400, a constant distance is maintainedbetween the holding frame 300 and the cover plate 500.

The cover plate 500 has a planar shape. To prevent distortion orbending, the cover plate 500 may preferably be formed of a rigidmetallic material. As illustrated in FIG. 1, the cover plate 500 iscoupled to the upper portion of the holding frame 300. As describedabove, due to the gap members 400 installed on the holding frame 300,the holding frame 300 and the cover plate 500 are maintained at auniform distance.

A filling hole 510 and a coupling hole 520 are formed in the cover plate500. One filling hole 510 and a plurality of coupling holes 520 areformed in the cover plate 500 at each of positions respectivelycorresponding to the heat storage units 100. As described above, twelveheat storage units 100 are held in the holding frame 300. A total oftwelve filling holes 510 corresponding to the twelve heat storage units100 are formed in the cover plate 500.

The filling hole 510 communicates with an injection inlet 160 of theheat storage units 100. The filling hole 510 is arranged at a positioncorresponding to the heat storage units 100 arranged via the unit guides311 of the holding portion 310. Accordingly, when the cover plate 500 iscoupled to the holding frame 300, a heat storage material may beinjected into the injection inlet 160 of the heat storage units 100through the filling hole 510 of the cover plate 500.

The coupling holes 520 are holes, through which a bolt for coupling theheat storage units 100 to the cover plate 500 passes. By inserting abolt through the coupling holes 520 to fasten the bolt to the heatstorage units 100, the heat storage units 100 are coupled to the coverplate 500. When coupling between the cover plate 500 and the heatstorage units 100 is completed, upper surfaces of the heat storage units100 and a lower surface of the cover plate 500 are closely adhered toeach other. While coupling the cover plate 500 and the heat storageunits 100 to each other via a bolt, the heat storage units 100 arelifted and the lower surfaces of the heat storage units 100 areseparated from the holding portion 310.

Referring to FIG. 4, a distribution member 600 is installed in thefilling chamber 210. The distribution member 600 includes a plurality ofdistribution holes 620 and a distribution flow passage 610.

The distribution flow passage 610 is a pipe formed inside thedistribution member 600, and hot water may move through the distributionflow passage 610. The distribution flow passage 610 connects the inlet220 of the heating case 200 and the distribution holes 620 of thedistribution member 600. Hot water that has flown into the inlet 220flows to the distribution holes 620 through the distribution flowpassage 610. The distribution holes 620 are holes formed in thedistribution member 600 to communicate with the filling chamber 210. Hotwater is evenly distributed into the filling chamber 210 through theplurality of distribution holes 620. As illustrated in FIG. 4, an innerdiameter of each of the distribution holes 620 may preferably increaseaway from the inlet 220.

A checking member 700 has a bar shape. Measurement is marked on thechecking member 700 in a length direction. The checking member 700 maybe inserted into the injection inlet 160 of the heat storage units 100through the filling hole 510 of the cover plate 500.

Next, referring to FIG. 5, a structure of the heat storage units 100used in the apparatus for filling a heat storage material, according tothe present embodiment, will be described.

The heat storage units 100 include a unit main body 110 having acylindrical shape and extending in a length direction. A heat storagechamber formed as a closed space is formed inside the unit main body110. A heat storage material is filled in the heat storage chamber. Theinjection inlet 160 communicating with the heat storage chamber isformed in the unit main body 110. Accordingly, a heat storage materialmay be filled in the heat storage chamber through the injection inlet160. A coupling port 170, to which a bolt inserted through the couplingholes 520 of the cover plate 500 is fastened, is formed in the uppersurfaces of the heat storage units 100.

Meanwhile, a plurality of internal pins are installed in the heatstorage chamber. The internal pins are formed to protrude and extendfrom an inner surface of the heat storage chamber toward a center of theheat storage chamber. The internal pins are arranged radially withrespect to the unit main body 110 to protrude. In addition, a pluralityof uneven structures may be formed on surfaces of the internal pins toincrease an area of contact between a heat storage material and theinternal pins, thereby enhancing heat exchange efficiency. A pluralityof external pins 140 are installed on an external surface of the unitmain body 110. The external pins 140 may be arranged in acircumferential direction along the external surface of the unit mainbody 110 to protrude in a radial direction.

Hereinafter, an operation of filling a heat storage material in the heatstorage units 100 by using the apparatus for filling a heat storagematerial configured as described above will be described.

First, the twelve heat storage units 100 are placed in the holding frame300. A user places the heat storage units 100 such that the lowersurfaces of the heat storage units 100 meet the holding portion 310 ofthe holding frame 300. Here, some of the heat storage units 100 areinserted into the unit guide 311 of the holding portion 310 as describedabove. Accordingly, the twelve heat storage units 100 are held in theholding frame 300 while they are in an arrangement as illustrated inFIG. 1.

After placing the twelve heat storage units 100 in the holding frame300, the cover plate 500 is coupled to the upper portion of the holdingframe 300. Due to the gap members 400, there is a distance between thecover plate 500 and the holding frame 300.

As described above, the filling hole 510 and the coupling holes 520 ofthe cover plate 500 are arranged at positions corresponding to the heatstorage units 100 aligned via the unit guides 311. When the cover plate500 and the holding frame 300 are coupled to each other, one fillinghole 510 and a plurality of coupling holes 520 correspond to each of theheat storage units 100.

When a bolt is fastened to the coupling port 170 of the heat storageunits 100 via the coupling holes 520 of the cover plate 500, the coverplate 500 and the heat storage units 100 are coupled to each other. Asdescribed above, as there is a distance between the cover plate 500 andthe holding frame 300 due to the gap members 400, the heat storage units100 are lifted while coupling the heat storage units 100 to the coverplate 500. Accordingly, when the heat storage units 100 are completelycoupled to the cover plate 500, the lower surfaces of the heat storageunits 100 are spaced apart from the holding portion 310 of the holdingframe 300.

Due to the action of the gap members 400 as described above, the heatstorage units 100 are firmly fixed to the cover plate 500, and spaceaccommodating changes in the measurement of the heat storage units 100due to thermal expansion is also provided.

Next, an operation of filling hot water in the filling chamber 210 ofthe heating case 200 will be described.

Hot water is supplied to the heating case 200 by using a pump (notshown) and a heater (not shown). Hot water flows through the inlet 220to the distribution flow passage 610 of the distribution member 600connected to the inlet 220. The hot water flowing through thedistribution flow passage 610 is distributed into the filling chamber210 of the heating case 200 through the plurality of distribution holes620 connected to the distribution flow passage 610. As described above,as hot water flowing in the distribution flow passage 610 is supplied tothe filling chamber 210 through the plurality of distribution holes 620,the hot water may be evenly distributed into the filling chamber 210.

When the hot water filled in the filling chamber 210 exceeds a certainlevel, the hot water is discharged through the outlet 230 arranged inthe upper portion of the filling chamber 210 and flows to a pump (notshown). In sum, the hot water that has flown into the filling chamber210 through the inlet 220 is discharged to the outside through theoutlet 230. As described above, as the hot water filled in the fillingchamber 210 of the heating case 200 is continuously circulated, the hotwater filled in the filling chamber 210 may be maintained at a certaintemperature.

Meanwhile, in order to evenly supply hot water not only into thedistribution holes 620 adjacent to the inlet 220 but also to thedistribution holes 620 that are relatively far from the inlet 220, aninner diameter of the distribution holes 620 that are relatively farfrom the inlet 220 may preferably be larger than an inner diameter ofthe distribution holes 620 that are relatively close to the inlet 220.By using this method, an internal temperature of the filling chamber 210may be maintained uniform.

When hot water is filled in the filling chamber 210 of the heating case200 according to this process, an assembly in which the heat storageunits 100 are held and the holding frame 300 and the cover plate 500 arecoupled to each other is inserted into the filling chamber 210 of theheating case 200. The assembly including the heat storage units 100, theholding frame 300, and the cover plate 500 may be inserted into thefilling chamber 210 of the heating case 200 by using various methods. Inthe present embodiment, the assembly is inserted into the fillingchamber 210 by using a crane.

When the holding frame 300 is seated in the filling chamber 210 of theheating case 200, the twelve heat storage units 100 held in the holdingframe 300 are arranged inside the filling chamber 210 of the heatingcase 200. The heat storage units 100 are heated by hot water filled inthe filling chamber 210 of the heating case 200. After the heat storageunits 100 are sufficiently heated, a heat storage material in a solidstate is injected into each of the heat storage units 100 through thefilling hole 510 of the cover plate 500. The heat storage material thathas passed through the filling hole 510 is filled in the heat storagechamber through the injection inlet 160 of the heat storage units 100.

The heat storage material filled in the heat storage chamber is heatedby the hot water filled in the filling chamber 210 of the heating case200, and when a temperature of the heat storage material increases to amelting point or higher, the heat storage material is melted to a liquidstate. Temperatures of the heat storage units 100 and the heat storagematerial in the heat storage units 100 are maintained at a hightemperature due to the hot water in the filling chamber 210.Accordingly, a heat storage material that has been injected into theheat storage chamber relatively early is not cooled and maintains itsliquid state. Thus, the filling operation may be performed whilemaintaining the liquid state of the heat storage material until the heatstorage chamber is completely filled with the heat storage material. Inaddition, as the filling operation may be performed while simultaneouslyheating the twelve heat storage units 100, the filling operation of theheat storage units 100 may be performed quickly and efficiently.

As described above, when the heat storage units 100 are heated and theheat storage material is simultaneously melted, due to thermal expansionof a material, of which the heat storage units 100 are formed, and anincrease in a volume of the heat storage material filled in the heatstorage units 100, the volume of the heat storage units 100 mayincrease. As described above, the heat storage units 100 are coupled tothe cover plate 500 while they are spaced apart from the holding portion310, and the inner diameter of the unit guides 311, into which some ofthe heat storage units 100 are inserted, is also greater than across-section of the heat storage units 100. This configuration isprovided in consideration of the increase in the volume of the heatstorage units 100 occurring during the filling operation. That is,according to the apparatus for filling a heat storage material of thepresent embodiment, damages to elements adjacent to the heat storageunits 100 due to the increase in the volume of the heat storage units100 when the elements come into contact with the heat storage units 100may be effectively prevented.

The user may use a checking member 700 to check a filling level of aheat storage material. When the checking member 700 is inserted into thefilling hole 510 of the cover plate 500, a surface of the checkingmember 700 is smeared with the heat storage material. The user may checka level of filling of the heat storage material by identifying themeasurement marked on the surface of the checking member 700 and aportion smeared with the heat storage material.

Meanwhile, an additional apparatus for injecting a heat storage materialsimultaneously into the twelve filling holes 510 may be used to use theapparatus for filling a heat storage material according to the presentembodiment.

When filling the heat storage units 100 with a heat storage material iscompleted according to this process, a fixed-type crane is operated tolift the holding frame 300 to separate the holding frame 300 from theheating case 200.

When a temperature is varied during the operation of filling a heatstorage material, due to a change in a density of the heat storagematerial, a filling level of the heat storage material in each of theheat storage units 100 may be different. Thus, in order to fill an equalamount of heat storage material, it is important to inject a heatstorage material in a constant temperature state. According to theapparatus for filling a heat storage material of the present embodiment,a heat storage material is filled while a temperature is maintained asdescribed above, and thus, a uniform amount of heat storage material maybe filled.

In addition, according to the apparatus for filling a heat storagematerial of the present disclosure, as a heat storage material may befilled into a plurality of heat storage units 100 at the same time, timeand costs needed for a filling operation may be remarkably saved. Thus,the unit cost of the heat storage units 100 may be reduced.

According to the apparatus for filling a heat storage material of thepresent disclosure, a method of melting a heat storage material by usinghot water is used, and thus, the method is safe compared to a method ofdirectly injecting a melted heat storage material. In addition,according to the apparatus for filling a heat storage material of thepresent disclosure, a filling apparatus and a filling process may beconfigured relatively simply.

While the present disclosure has been described with reference topreferred embodiments, the scope of the present disclosure is notlimited to the above described and illustrated forms.

For example, while the inlet 220 of the heating case 200 is described asbeing arranged in the lower portion of the filling chamber 210, and theoutlet 230 is described as being arranged in the upper portion of thefilling chamber 210 above, the opposite is also possible. That is, anoutlet may be arranged in a lower portion of a filing chamber, and aninlet may be arranged in an upper portion of the filling chamber.Moreover, an apparatus for filling a heat storage material according tothe present disclosure may also be configured by installing an outletand an inlet at a same height.

In addition, while the heat storage units 100 and the cover plate 500are described above as being coupled via a bolt passing through thecoupling holes 520, heat storage units and a cover plate may be coupledusing various well-known methods other than a bolt coupling method.

In addition, twelve heat storage units 100 held in the holding frame 300are described above as an example. Accordingly, twelve unit guides 311included in the holding portion 310 and twelve filling holes 510 of thecover plate 500 are described. However, the number of heat storage unitsto be held in a holding frame may be modified in various manners, andthe number of unit guides, filling holes, and coupling holes may also bemodified in various manners.

In addition, while the unit guides 311 of the holding portion 310 aredescribed as being formed to simply correspond to a cross-section of theheat storage units 100 such that the heat storage units 100 are insertedinto the unit guides 311, unit guides may also be configured to fix heatstorage units inserted into the unit guides so that the heat storageunits are not rotated about a length direction as an axis. For example,grooves of unit guides and protrusions of heat storage units may beconfigured to be coupled to each other so as to fix a position of theheat storage units inserted into the unit guides. In addition, unitguides may also be omitted.

In addition, while the gap members 400 are described as being coupled tothe holding frame 300, an apparatus for filling a heat storage materialaccording to the present disclosure may also be configured such that agap member is coupled to a cover plate. An apparatus for filling as heatstorage material according to the present disclosure may also beconfigured by omitting a gap member.

In addition, while the heat storage units 100 coupled to the cover plate500 are described above to be separated from a holding portion of aholding frame via the gap members 400, the same effects may also beobtained by adjusting heights of a cover plate and heat storage units.For example, a holding frame may be configured to have a higher heightthan heat storage units. In this case, when the heat storage units arecoupled to the cover plate, the heat storage units are lifted in acoupling operation, and thus, the heat storage units are separated fromthe holding portion of the holding frame.

In addition, the form of the holding frame 300 described and illustratedabove is merely an example, and the form of a holding frame of theapparatus for filling a heat storage material according to the presentdisclosure may be modified in various manners.

In addition, while the distribution holes 620 of the distribution member600 are described above to have different inner diameters from eachother, a distribution member including distribution holes having auniform inner diameter may also be configured. In addition, an apparatusfor filling a heat storage material according to the present disclosuremay also be configured by omitting a distribution member.

In addition, a structure of the heat storage units 100 described aboveis merely an example, and the apparatus for filling a heat storagematerial according to the present disclosure may be used to fill varioustypes of heat storage systems.

According to the apparatus for filling a heat storage material of thepresent disclosure, an accurate and uniform amount of a heat storagematerial may be conveniently filled in a heat storage system whilemaintaining a liquid state of the heat storage material by melting heatstorage material.

In addition, according to the apparatus for filling a heat storagematerial according to the present disclosure, the time and costs neededfor an operation of filling a heat storage material in a plurality ofheat storage systems may be saved.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While one or more embodiments have been described with reference to thefigures, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the inventive concept as definedby the following claims.

What is claimed is:
 1. An apparatus for filling a heat storage material,the apparatus being formed in a form of a container for storing heat byusing a thermal energy delivery method, wherein the heat storagematerial is filled in a heat storage unit having an injection inletformed in an upper portion of the heat storage unit, the apparatuscomprising: a heating case comprising a filling chamber having an openedupper portion, an inlet through which hot water is supplied to thefilling chamber, and an outlet formed in the filling chamber, whereinthe hot water that has flown into the filling chamber is dischargedthrough the outlet; a holding frame comprising a holding portion onwhich the heat storage unit is held, wherein the holding frame entersthe upper portion of the heating case to be seated in the fillingchamber of the heating case; a cover plate comprising a filling holecommunicating with the injection inlet of the heat storage unit so as tofill the heat storage material through the injection inlet of the heatstorage unit, wherein the cover plate is coupled to the holding frame;and a gap member disposed between the holding frame and the cover plateand installed on one of the holding frame and the cover plate, such thatthe cover plate is coupled to the holding frame while maintaining adistance with respect to the holding frame, wherein the holding portionof the holding frame comprises a unit guide having a shape correspondingto a lower surface of the heat storage unit such that a position of theheat storage unit with respect to the cover plate is aligned.
 2. Theapparatus of claim 1, wherein a coupling hole, through which a boltcoupling the heat storage unit held on the holding portion of theholding frame and the cover plate to each other passes through, isformed in the cover plate.
 3. The apparatus of claim 1, wherein theinlet of the heating case is arranged in a lower portion of the filingchamber, and the outlet of the heating case is arranged in an upperportion of the filing chamber.
 4. The apparatus of claim 3, furthercomprising a distribution member installed in the filling chamber andcomprising a plurality of distribution holes, through which the hotwater flowing through the inlet is distributed into the filling chamber,and a distribution flow passage connecting the plurality of distributionholes and the inlet of the heating case.
 5. The apparatus of claim 4,wherein an inner diameter of the plurality of distribution holes of thedistribution member increases away from the inlet of the fillingchamber.
 6. The apparatus of claim 1, further comprising a checkingmember inserted into the heat storage unit through the filling hole ofthe cover plate to check a level of filling of the heat storagematerial.
 7. The apparatus of claim 6, wherein a measurement is markedon the checking member in a length direction.